Idiopathic pressure is secondary to increased venous sinus pressure.
Predilection for young women who are likely to be obese.
More than 95% of patients with idiopathic intracranial, hypertension, are women of child bearing age with obesity.
Men are seldom affected.
It is a rare process occurring in about one is 500 female persons with the BMI higher than 30.
The prevalence in individuals older than 70 years is 1 to 1.5%.
The prevalence of the disease is rising related to surging obesity rates.
A history of recent weight gain often precedes the onset of symptoms.
It can occur in children before puberty but the association with obesity and female sex is less marked.
Idiopathic intracranial hypertension is related to elevated intracranial pressure without a known cause.
Diagnosis includes: symptoms of elevated intracranial pressure, such as headache, tinnitus, diplopia, and/or visual disturbances without secondary etiologies, edema on fundus examination and elevated CSF pressure on lumbar puncture performed in the lateral decubitus position, with an opening pressure of greater than 25 cm of water in adults and greater than 28 cm of water in children.
Before diagnosis other potential causes of raised intracranial pressure are considered.
Tetracycline class antibiotics and retinoids can rarely induce secondary forms of intracranial hypertension.
Vascular disorders such as cerebral venousnsinus thrombosis and dural ateriovenous fistula can mimic idiopathic intracranial hypertension.
Headache is the most common initial symptom, occurring in 84% of patients.
Headache pain is constant or daily in approximately half of affected patients.
A history of migraine is common in IIH.
Chronic daily headaches, normal neurological examination (except for papilledema) and normal lab examination (except for an empty sella).
May have a severe lateralizing pulsatile headache, with intracranial noises, double vision, and nausea.
Transient visual obscuration occurs in 68% of patients, neck or back pain in 53%, pulse synchronous tinnitus in 52%, visual loss in 32% and diplopia in 18%.
IIH is an occasional cause of rhinorrhea or serous serious otitis media resulting from a CSF leak at the skull base.
Unremitting headaches with episodic worsening, accompanied by pulsatile tinnitus, transient visual difficulties and diplopia may occur.
Papilledema is the most important sign.
Visual loss caused by edema progresses, gradually from the periphery of the visual field.
Central acuity is affected last.
Any reduction in acuity suggest substantial damage to the optic nerve.
Intervention is crucial because the greatest threat posed by idiopathic intracranial hypertension is irreversible blindness.
Occasionally six nerve palsy may be noted, but the neurologic examination is usually otherwise normal.
It primarily affects women of child bearing age.
IIH is associated strongly with obesity.
IIH prevalence has increased to 9.9 per 100,000 in 2022, and correlates with increasing US obesity rates.
Reports of familiar idiopathic, normal pressure hydrocephalus have described pedigrees with autosomal dominant transmission.
Its pathogenesis may be related to hypersecretion and/or decreased absorption of CSF related to increase levels of androgens, glucocorticoids, glucagon-like peptide, and inflammatory cytokines associated with central opacity.
Visual acuity is preserved until late in the course of the illness.
Bilateral optic disc edema is often present.
The CSF has an opening pressure of greater than 25 cm of water when measured with the patient in the lateral decubitus position, and the CSF is normal.
Occasional patients with idiopathic intracranial hypertension have an opening pressure of less than 25 cm of water.
Neuroimaging includes a normal brain MRI.
With papilledema of moderate to severe degree lumbar puncture and removing a generous volume of CSF of 30 to 40 cc cc lowers ICP immediately and protects the discs from damage.
Treatment:
Treatment includes weight reduction, surgical treatment with either lumbar to peritoneal shunting, or fenestration of the optic nerve sheath, deep venous sinus shunt, CSF shunting and lowering of intracranial pressure with acetazolamide.
Surgical intervention is necessary when visual acuity has become reduced in a pace of vision loss is too rapid to wait for edema to improve gradually through weight loss and treatment with acetazolamide.
In fenestration of the optic nerve sheath, an aperture is created in the optic nerve sheath just behind the globe relieving papilledema by allowing CSF to drain into the orbit.
CSF shunting remains the standard treatment for medically refractory IIH.
CSF shunt immediately reduces ICP to the normal range, protects the optic discs and allows acetazolamide treatment to be stopped.
First line management for IIH is a carbonic anhydrase inhibitor such as a acetazolamide, which causes a rapid reduction intracranial pressure by decreasing CSF production.
The combination of a carbonic anhydrase inhibitor and weight loss of 5 to 10% is effective in improving peripheral vision, papilledema, and vision quality of life measures.
Topiramate, another carbonic anhydrase blocker can reduce ICP.
Glucocorticoids have no role in treatment.
Bariatric surgery and GLP-one receptor agonists have demonstrated decreased intracranial pressure compared with control patients.
GLP-1 and gastric inhibitory polypeptide agonist can induce weight loss and reduce ICP.